The `overwriteVars` option is optional and expects a boolean. If this option is enabled it will overwrite all defined variables within the dependency config with the values of the variables defined in the base config. Variables that are not used or not defined within the base config aren't overwritten in the dependency config.

For example:
```yaml
# devspace.yaml
vars:
- name: DEFINED_AND_USED
  value: my-base-value
- name: DEFINED_AND_NOT_USED
  value: my-other-base-value
dependencies:
- name: dep1
  source:
    path: dep1
  overwriteVars: true
  # If overwriteVars is true, all variables that are used within this
  # config are passed to the dependency and will overwrite the values of variables with 
  # the same name there. In this case only the variable DEFINED_AND_USED
  # will be passed to the dependency, as DEFINED_AND_NOT_USED is not used within the config.
  # overwriteVars: true
  #
  # If you want to pass the variable DEFINED_AND_NOT_USED to the dependency as well,
  # you can either use it somewhere within the config or explicitly pass it to the dependency with vars.
  # vars:
  # - name: DEFINED_AND_NOT_USED
  #   value: ${DEFINED_AND_NOT_USED}
deployments:
- name: deployment
  helm:
    componentChart: true
    values:
      containers:
      - image: ${DEFINED_AND_USED}
```

and

```yaml
# dep1/devspace.yaml
vars:
- name: DEFINED_AND_USED
  value: my-dep-value
- name: DEFINED_AND_NOT_USED
  value: my-other-dep-value
deployments:
  # This will be my-other-dep-value
- name: ${DEFINED_AND_NOT_USED}
  helm:
    componentChart: true
    values:
      containers:
        # This will be my-base-value
      - image: ${DEFINED_AND_USED}
```
